Send to:

Choose Destination
See comment in PubMed Commons below
J Neurosci. 2004 Jan 7;24(1):35-42.

Production of resurgent current in NaV1.6-null Purkinje neurons by slowing sodium channel inactivation with beta-pompilidotoxin.

Author information

  • 1Northwestern University Institute for Neuroscience, Northwestern University, Evanston, Illinois 60208, USA.


Voltage-gated tetrodotoxin-sensitive sodium channels of Purkinje neurons produce "resurgent" current with repolarization, which results from relief of an open-channel block that terminates current flow at positive potentials. The associated recovery of sodium channels from inactivation is thought to facilitate the rapid firing patterns characteristic of Purkinje neurons. Resurgent current appears to depend primarily on NaV1.6 alpha subunits, because it is greatly reduced in "med" mutant mice that lack NaV1.6. To identify factors that regulate the susceptibility of alpha subunits to open-channel block, we voltage clamped wild-type and med Purkinje neurons before and after slowing conventional inactivation with beta-pompilidotoxin (beta-PMTX). beta-PMTX increased resurgent current in wild-type neurons and induced resurgent current in med neurons. In med cells, the resurgent component of beta-PMTX-modified sodium currents could be selectively abolished by application of intracellular alkaline phosphatase, suggesting that, like in NaV1.6-expressing cells, the open-channel block of NaV1.1 and NaV1.2 subunits is regulated by constitutive phosphorylation. These results indicate that the endogenous blocker exists independently of NaV1.6 expression, and conventional inactivation regulates resurgent current by controlling the extent of open-channel block. In Purkinje cells, therefore, the relatively slow conventional inactivation kinetics of NaV1.6 appear well adapted to carry resurgent current. Nevertheless, NaV1.6 is not unique in its susceptibility to open-channel block, because under appropriate conditions, the non-NaV1.6 subunits can produce robust resurgent currents.

[PubMed - indexed for MEDLINE]
Free full text

LinkOut - more resources

Full Text Sources

Other Literature Sources

PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk